Inverse correlation between FBXW7/hCDC4-β mRNA expression and promoter methylation in tumor cell lines. (a) Cancer cell lines were divided into two groups based on the ratio of band intensity of McrBc digested cell line DNA divided by undigested DNA. The expression levels were lower in the methylated (M) group than in the unmethylated (UM) group (P = 0.0001). Horizontal lines, median expression value of each group. P value was calculated using the nonparametric Mann-Whitney U test. (b) 5-aza-dC treatment upregulate FBXW7/hCDC4-β mRNA levels in methylated cell lines. Mean ± SD. (c) 5-aza-dC demethylate the FBXW7/hCDC4-β promoter as evident by restoration of PCR amplification of McrBc digested DNA. (d) pGL3E luciferase reporter assay without or with FBXW7/hCDC4-β promoter region in vitro methylated using SssI enzyme (filled bars). Relative fold change in luciferase activity +/- SEM is shown.